A belt retractor with the above-mentioned features is described in DE 103 60 032 A1. In order to prevent a blocking mechanism of the belt retractor from blocking a belt spool at the end of the winding of a safety belt after the safety belt has been taken off by a vehicle occupant and the safety belt is rolled up under the action of a winding spring (or when the safety belt is abruptly braked), the above-mentioned publication provides a cutoff (or disabling) of the belt-webbing-sensitive and the vehicle-sensitive control system so that an undesired blocking of the belt shaft at the end of the winding of the safety belt is prevented.
For this, in the known belt retractor, a locking disc is arranged on the belt shaft and is rotatable therewith, wherein the locking disc controls, by means of a guide curve arranged on it, a locking lever which is swivellably mounted in a fixed manner relative to the housing of the belt retractor. In a functional range in which almost the entire safety belt is wound on the belt shaft, the locking lever acts directly on a sensor lever of a vehicle sensor cooperating with a control disc, and secures it, thereby cutting off the vehicle-sensitive control system. Insofar as the belt-webbing-sensitive control system is realized by the control disc, wherein the control disc is constructed with a corresponding mass moment of inertia, a blocking catch mounted on the belt shaft is provided to cut off the belt-webbing-sensitive control system. For its actuation, the blocking catch is coupled via a guide link to the locking lever for the cutoff of the vehicle sensor. When the blocking catch is in its blocking position, brought about by the locking position of the locking lever, it is in engagement with the control disc and locks the control disc so as to be locked against relative rotation with the belt shaft.
Furthermore, the known belt retractor has an Automatic Locking Retractor (ALR) and/or an Emergency Locking Retractor (ELR) switchover for setting a child safety function, which is controlled by the locking disc by means of switching (or trip) cams constructed thereon. In the ALR switching position, which is activated by almost complete withdrawal of the safety belt for securing a child's seat to the vehicle seat, the control disc is locked on a toothing fixed to the housing, so that on withdrawal of the seat belt in the ALR switching position, owing to the stationary control disc, a blocking of the belt retractor is immediately triggered.
The known belt retractor entails the disadvantage that for the cutoff of both the vehicle-sensitive and of the belt-webbing-sensitive control system, various levers are provided, whereby the construction of the belt retractor is complicated and the manufacturing expenditure is correspondingly great. In addition, the cutoff of the two control systems can only take place in succession, because the actuation of the locking lever for the vehicle sensor is a precondition for the controlling of the blocking catch for the belt-webbing sensitive control system. As several control processes are necessary, there exists a corresponding potential for error.
Therefore, one object of the present invention is to simplify a self-locking belt retractor with regard to the cutoff of the vehicle-sensitive and also of the belt-webbing-sensitive control system, and to improve the reliability of the cutoff function accordingly.
The solution to this task, including advantageous developments and further developments of the invention, can be seen from the content of the claims, which follow this description.